• Nineteen rhesus monkeys between the ages of 5.9 and 8.5 months were separated from their mothers in five different studies. While in two of the studies, data indicated behavioral responses roughly parallel to Bowlby's protest-despair response to maternal separations, data across all five studies were sufficiently variable to bring this technique into serious question as a reliable and predictable animal model for neurobiologic and rehabilitative studies.
Lewis JK, McKinney WT, Young LD, Kraemer GW. Mother-Infant Separation in Rhesus Monkeys as a Model of Human DepressionA Recopnsideration. Arch Gen Psychiatry. 1976;33(6):699-705. doi:10.1001/archpsyc.1976.01770060035006